Sonic method and apparatus for surface mining mineral beds or the like



May 8, 1962 A. G. BODINE some METHOD AND APPARATUS FOR SURFACE MININGMINERAL BEDS OR THE LIKE Filed Nov. 15, 1961 2 Sheets-Sheet 1 ALBERT G.BODINE ATTORNEYS A. G. BODINE 3,033,543 SONIC METHOD AND APPARATUS FORSURFACE MINING MINERAL BEDS OR THE LIKE May 8, 1962 2 Sheets-Sheet 2Filed Nov. 15, 1961 INVENTOR.

ALBERT G. BODINE BY g ATTORNEYS 3,033,543 SONIC METHOD AND APPARATUS FORSURFACE MINING MlNERAL BEDS OR THE LIKE Albert G. Bodine, 13120 MoorparkSt., Sherman Oaks, Calif. Filed Nov. 15, 1961, Ser. No. 152,601 7Claims. (Cl. 26213) This invention relates generally to sonic waveprocesses and apparatus for surface mining of minerals or the like, anddeals more particularly with application to a bed of mineral of asonically vibratory bit in such a manner as to break away particles ofthe mineral in predetermined size ranges.

This application is a continuation-in-part of my earlier applicationentitled Sonic Wave Earth Digging and Moving Machines, Serial No.839,196, filed September 10, 1959, and allowed September 7, 1961.

The general object of the invention is the provision of a method andapparatus, of sonic wave character, for planing the surface of a bed ofmineral surface in such manner as to rapidly take a cut of the order ofseveral inches in depth, yielding mineral fragments within apredetermined size range, which may be of sufficiently small grading asto dispense with the necessity of a rock crusher at the site of theoperation.

Many mineral deposits, such as limestone, dolomite, borax, perlite,coal, etc., occur naturally in beds which can be planed, so to speak, bya properly manipulated sonically vibrating tool. The process of theinvention employs a bit on a resonant elastically sonically vibratorymember, such as an elongated steel bar. The vibration pattern ispreferably longitudinal of the bar, suchas a half-wavelengthlongitudinal standing wave mode. The bar and the bit are preferablyoriented at a fairly sharp acute angle to the surface of the mineral tobe mined, and the bit is guided so as to make a cut of predetermineddepth, such as of the order of two or three inches, for example. Thesonically vibratory bit is applied -to the mineral, in such attitude,and'pressure is exerted to force the bit against the deposit.Substantial sonic wave energy is thereby expended upon the mineraldeposit, and the mineral breaks into fragments by elastic fatigue. Byreason of attitude of the guided bit, a step-cut or shoulder is formedas the bit is moved against the formation, yielding fragments within apredetermined size range depending upon the depth at which the bit isguided.

The bit is vibrated against the shoulder-of the formation by a sonicelastic vibration pattern set up in the bar that carries the bit. Thebar is composed of a good-grade of alloy steel, and the vibrationpattern ispreferably a longitudinal mode of standing wave vibration. a

This sonic pattern is thus acoustically coupled to the mineral in aparticular way which results in a surprising rate of elastic fatiguefailure, apparentlydue to the acute angle which engenders cyclic tensionwaves in the mineral. These tension waves are equally spacedbetween veryhigh amplitude compression waves, and the resulting as symetricalwaveform gives rapid fatigue.

In a preferred form, the bar is mounted on'a suitable transport vehicleat or near its midpoint, and is set into half-wavelength standing wavevibration, the wave generator most conveniently and effectively beingmounted on the rearward ends of the bar. If the generator deliversalternating forces to the rearward end of the bar in a directionlongitudinally thereof and at a frequency 1 equal to S/2L, where S isthe speedof sound in the material of the bar, and L is its length, thebar will undergo resonant longitudinal half-wavelength standingwave-vibration. Such a bar is known in the science of acoustics as ahalf-wavelength bar, The theory of longitudinal waves in bars is wellunderstood in the science of acous- United States Patent 3,033,543Patented May 8, 1962 ICC length standing wave vibration, eachhalf-length of the bar alternately elastically elongates and contractsat the frequency of operation of the wave generator. It will beunderstood that the two half-lengthselastically elongate simultaneouslywith one another and elastically contract simultaneously with oneanother. 'The extent of elastic elongation or contraction is minimizedat the midpoint of the bar, and progressivelyincreases, for successiveincrements of length of the bar, from its midpoint to its twoextremities. In standing wave vibration of the type in question, thepoint of minimized vibration amplitude, at the midpoint of the bar, istermed a velocity node, and the two points of maximized vibrationamplitude, at the extremitiesof the bar, are termed velocity antinodes.It will be clear-that the bar does not vibrate bodily or as a whole.

Half-wavelength vibration must also be understood as a resonantphenomenon, occurring when the frequency of generator operation is suchthat the inertia reactance of the bar is equal to the elastic stiffnessreactance thereof. In the region of this resonance frequency, maximizedamplitude of vibration is attained at the extremities of the bar for awave generator of given power.

lnoperation, the bit on the forward end of the bar, engaged with themineral bed, and pressedthereagainst by the elfort exerted by thetransport vehicle, act to radiate into the mineral body sonic waveswhich may, depending upon their length, be for example of the order of400 to 1000 cycles per second, or thereabouts. Using a generator ofadequate power, and operating safely within the maximum stress to whichthe bar should be subjected, a vibration amplitude may be attained atthe bit ,The wave stress is of comparatively large amplitude, and

the repeated cyclic tension or rarefaction phase of the wave causes themineral to fail or disintegrate as a result of elastic fatigue. With acomparatively sharp acute angle between the bar and the surface of themineral bed, and with the bit guided to take a shallow cut, such as twoor three inches, or thereabouts, the material fractures and breaks awayprimarily above the edge of the bit, so as to form a shoulder againstwhich the bit may then work, and which is progressively broken back.

.It should be mentioned that the effectiveness of sonic wave radiationinto the mineral body, and therefore the rate of disintegration in theshoulder, depends directly efiiciency, and the actual wave form in themineral, de- 1 pends upon'tnean bit pressure against-the shoulder. Thisin turn depends, of course, upon the effort exerted upon the transportvehicle. That is to say, when-the transport vehicle is pushed orpropelled ahead, the bit is forced into pressural engagement withtheshoulder.

The invention will be better understood from the following detaileddescription of typical" means for carrying it into effect, referencebeing bad to the accompanying drawings, in which: 1

FIG. 1 is a side elevational viewof an illustrated .embodiment of theinvention;

FIG. 2 is a plan View of the embodiment shown in FIG. 1; i g 7 FIG. 3 isan enlarged fragmentary View taken from a portion of FIG 1 with partsbroken away;

of the invention; and

. such as shown;

FIG. 5 is a longitudinal sectional view through the upper rearwardextremity of a bar of the machine of FIG. 4, showing the generator inelevation and the generator casing in section.

Reference being first directed to the embodiment of the, inventionsomewhat diagrammatically shown in FIGS. 1-3, numeralltl designatesgenerally a transport vehi' cle having a main frame 11 comprised of twoparallel longitudinal members 12, convergent at their forward ends, andincluding at theirrearward ends a transverse member 13 by which thevehicle may be pushed by another vehicle, not shown. The convergentforward end portions 14 of members 12 merge into a tongue 15 formed withan eye 16 which may receive a ,drag element or prong 16a projecting fromthe draw bar 16b of a towing vehicle, not shown.

Frame 11 is provided with steerable front wheels 17 and with rearwardwheels 18.

A rectangular sub-frame 20 is pivotallymounted on pivot pins 21 mountedin brackets 22 secured underneath frame members 12 at about themidpoints of said members, and is adjustably swingable between themembers 12. This sub-frame may comprise longitudinal members 23 andfront and rearward end members 24 and 25, respectively. The main portionof the frame 20, from its pivoted forward end to a point a little shortof its rearward end, is normally in an inclined position, making arelatively sharp acute angle with horizontal,

32, which may be, for example, conventional piston and cylinderhydraulicjacks, equipped with hand pumps, not shown.

Supported at its midpoint in a fixture 40 carried by sub-frame 20,and'extending generally parallel to the sub-frame, is an elastic bar 41,composed preferably of a good grade of alloy steel. This bar carries atits forward end a bevelled bit 42. The coupling between the bit and thebar 41 may comprise a threaded pin 43 on thebit screwed into a threadedbox in the end of the bar. The bit preferably flares from its couplingend to a bevelled blade, as illustrated.

Mounted onthe rearward end of bar 41 is a vibration generator 45 forsetting up a longitudinal vibration pattern in the bar 41. Itmay be of aconventional type having a housing 46 mounting parallel shafts 47carrying, insidethe housing,-a pair of meshing spur gears 48, andoutside the housing, a pair of unbalanced weights '49. One of'the shafts47 is'coupled, through a shaft 50, universal joints 51, and a gearbox52, with the drive shaft of engine 28. The unbalanced weights 49, whichturn in opposite'directions, are so phased as'to move toward and'fromone another in unison, and longitudinallyof bar 41 in unison. Thelateral components'of vibratory force-developed thereby thereforecancelout, while the vibratory forces longitudinal of the bar are additive,and are applied through the generator housing to the end of the bar 41.

In accordance with principles discussed fully in the introductoryportion of the specification, the vibration generator is driven .byengine 28 through gear box 52 at a resonant frequency of the bar 41, soas to establish a longitudinal standing wave pattern in the bar,preferably of substantially half-wavelength.

The bit 42 is thereby set into vibration in a direction longitudinallyof the bar, moving throughashort stroke,

The rearward end portion 26 of the,

amounting to a small fraction of an inch, but with high force.

To add weight to the transport vehicle, near its middle, so as to assurethat the bit will be held down against the mineral bed to be planed, Iprefer to equip the vehicle, near its midpoint, with a large tank 60,which can be filled with water.

A further desirable feature is the provision, rearwardly of the bit, of'anangularly disposed scraper blade 62, adapted to catch the materialfragmented by the bit and move it to one side. The blade may be hungfrom the frame members 12, with capability for vertical adjustment, byhanger screws 64' threaded in frame lugs 65,-

and tightened by jamb nuts 66. The lower ends of these screws will beunderstood to .be swivelled to the blade.

When the vehicle 10 is' being transported from place to place, thescraper blade is elevated, and the subframe 20 tilted so as to raise thebit.42 out of ground engagement, this latter being accomplished, ofcourse, by proper manipulation of the jacks 32.

To initiate operation, the sub-frame is tilted toward the position ofFIG. 1, at first, so to take a relatively shallow cut, or so as just toengage firmly against the surface of themineral bed 13 to be planed. Theengine is then started and driven at a speed to set up a standing wavein the bar 41. The bit begins to work on the mineral, generatingpositive elastic waves therein, working through an amplitude of a smallfraction of an inch. As the bit begins to penetrate, or to cut a'notch,the angle of tilt can be somewhat increased, so as to deepen the out;and at this time, forward effort is exerted on the vehicle to force thebit against the mineral. The resultant line of pressure is thus at anacute angle to the surface of themineral bed. This forward effort on thevehicle can be supplied through a towing vehicle, or a pushing vehicle;or, of course, the vehicle 11? could be self-propelled. Thevforwardefiort against the vehicle 10, and therefore the increased pressure ofthe bit against the mineral bed, increases the acoustic coupling betweenthe bar and bit and the mineral bed, and increases the fragmentingaction of the hit against the mineral bed. The angle of tilt of thesub-frame and bar 41 can then be increased relative to the surface ofthe bed to take the desired cut, to a depth of say two to three inches,for example, while at the same time, the forward effort on the transportvehicle is increased. With this increased pressure, and under thesedescribed conditions. acoustic coupling is improved, and a shoulder s iscut into the mineral bed, and the bit works against this shoulder alonga pressure line having the same acute angle as the bar. The material ofthe bed in the general region in back of this shoulder is set intosonicwave activity, or sonic vibration, and the bit then maintains contactwith the shoulder throughout a large part, if not the entirety, of itsvibratory cycle. Under these conditions an assymetrical wave-pattern isgenerated in the mineral, having a predominanceof positive phase, butalso a desirable answer of negative phase. 7 p

The material of the bed in back of the shoulder, under the stressconcentration exerted by the edge of the bit, and-also because ofelastic fatigue due to the vibratory cycle set up therein, rapidlybreaks in fragments, the plane of severance being, in general, parallelto the surface of the bed, and at the depth of the forward edge of thebit. There is of course-substantial irregularity in this breakawayplane; but the shoulder s gradually recedes as the bit works against it,and the material breaks away, in

general, on a'rough planeat the bottom of the shoulder.

The great advantage is gained that the fragmented mineral tends to breakaway in fragments of somewhat uniform size range, small enough thattheusual rock crusher at the site can be dispensed with. i

and the horizontal, and showing a form in which the bits compriseintegral end portions of the vibratory bars. Here again the assymetricalwave action is accomplished, particularly with materials more adaptableto a larger acute angle.

A two-wheeled vehicle 120 has a fairly heavy platform 1.21. whichincludes a rearward portion 122 mounting a pair of longitudinallyvibratory steel bars 123, and a forward portion 124 coupled as at 125 tothe drag element 12-5 of a tractor machine, not shown. It will beunderstood that the element 126 is designed for vertical adjustmenttoaccomplish proper depth engagement of the lower extremities or bit endsof bars 123 with the mineral bed, or to elevate the bars 123sufficiently for adequate road clearance during towing when not inservice.

The bars 3123 are again half-wavelength standing wave vibration members,being tightly mounted at or near their midpoints in fittings 128 securedto platform 121 in positions inclined at acute angles to horizontal, asshown. The bit elements integrally formed with the forward extremitiesof the bars 123 are beveled, as indicated at 129, and the rearward orupper extremities of the bars carry vibration generators 139, which maybe of the same type shown in F168. 7 and 8 of my aforementionedapplication Serial No. 839,196. Referring to FIG. 5, generator casing132 is snugly embraced by pressure tight casing 133, including dome 134into which is coupled air supply conduit 135 leading from a suitablecompressor plant, not shown. The tubular air discharge and mounting stem136 of the generator is fitted tightly in the upper end of bar 123, andair is exhausted via passage 137 leading outwardly to one edge of bar123.

The generators 134} will be understood to be operated to set uphalf-wavelength standing wave vibration of the bars 123. in operation,platform 121 is manipulated to engage the relatively sharp edges 138 onthe forward and lower extremities of the bars with the mineral bed at acontrolled depth, causing disintegration of a layer of the mineral bedahead of the bars in accordance with principles heretofore explainedVibration generators of the type shown in F168. 1-3 may be used on theends of the bars 123, if desired. In such case, the driving engine canbe mounted on platform 21, and can be belt-connected with pulleys on thegenerator drive shafts, as will be fully understood without thenecessity of illustration.

It will of course be understood that the embodiments of the inventionillustrated and described herein are for illustrative purposes only, andthat various changes in design, structure and arrangement may be madewithout departing from the scope of the appended claims.

I claim:

1. The method of surface mining of minerals and the like comprisinggenerating a resonant vibration pattern in an elastic member which iscoupled to a bit, forcing said bit against said surface of said mineralwith an oblique angle whereby the resultant of said force bears an acuteangle relative to said surface so as to form a stepped shoulder in saidsurface, directing said resonant vibration pattern so as to transmitacoustic vibrations into said shoulder whereby acoustic fatigue of saidmineral is concentrated within said shoulder so as to form brokenparticles of said mineral having a predetermined size range.

2. The subject matter of claim 1, wherein the acute angle between theline of pressure exerted by the bit and the surface of the mineral isrelatively sharp.

3. The subject matter of claim 1, wherein the acute angle between theline of pressure exerted by the bit and the surface of the mineral thendoes not exceed substantially 30.

4. The subject matter of claim 1, wherein said elastic member comprisesan elastic bar, and the resonant vibration generated in said bar is alongitudinal standing wave.

5. Apparatus for surface mining of minerals and the like comprising, aresonant elastic member, a vibratory bit, havinga transversely disposedworking edge coupled to said elastic member, a sonic oscillator coupledto said resonant elastic member and operable at a resonant sound wavefrequency of said elastic member so as to generate a resonant vibrationpattern therein, which applies a vibration to said bit, guiding meansconnected to said reso nant member in supporting relationship so as toguide said bit along the exposed surface of said mineral at apredetermined depth setting and with the vibration path of said bitvibration bearing an acute angle with said surface of said mineral, andmeans for forcing said bit into acoustic coupling relationship with theprogressively formed shoulder in said mineral surface, whereby saidmineral is removed in a particle size of predetermined size range.

6. Apparatus for surface mining of a mineral bed or the like comprising,a transport vehicle adapted for forward travel over the surface of themineral bed, a vibratory bar disposed generally longitudinally of thevehicle and mounted on said vehicle with a downward inclination in adirection forwardlyof the vehicle, a bit on the forward end of said barhaving a transverse working edge engageable with the mineral bed, meansfor varying the angle of inclination of the bar to vary the acute anglemade by the bar with the surface of the mineral bed, and thereby theline of pressure application from the bit to the mineral bed, and asonic oscillator coupled to said bar so as to set up a longitudinalresonant vibration pattern therein.

7. Apparatus for surface mining of a mineral bed or the like comprising,a transport vehicle adapted for forward travel over the surface of themineral bed, a frame pivotally mounted on said vehicle on a horizontalpivot axis transverse of the vehicle, a vibratory bar disposed generallylongitudinally of the vehicle and mounted on said frame with a downwardinclination in a direction forwardly of the vehicle, a bit on theforward end of said bar having a transverse working edge engageable withthe mineral bed, means for adjustably raising and lowering said frameabout said pivot axis, whereby to vary the angle of inclination of saidbar relative to the surface of the mineral bed, a sonic vibrationoscillator mounted on and acoustically coupled to said bar, so as to setup a longitudinal vibration pattern therein, drive means on said framedrivingly coupled to said oscillator.

References Cited in the file of this patent UNITED STATES PATENTS Calosiet a1 May 29, 1956

